Thermostat.



G. F. JOHNSON. THERMOSTAT.

APPLICATION F ILED $1 11.30 1913. 1,099,923, Patented June 16, 1914;

UNITED s'ra'rns PATE FFICE.

CARL F. JOHNSON, 0F MILWAUKEE, WISCONSIN, ASSIGNOR TO JOHNSON SERVICE COMPANY, OF MILWAUKEE, VVISGONSIN, A CORPORATION OF WISCONSIN.

THERMOSTAT.

Specification of Letters Patent.

Patented June 16, 191%.

Application filed April 30, 1913. Serial No. 764,576.

To all whom it may concern:

Be it known that I, Cant, l1. Jormson, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of ll isconsin, have invented certain new and useful Improvements in Thermostats, of which the following is a specification.

This nvention relates to thermostatic temperature controlling devices and provides a means for setting said devices to any one of a plurality of standard temperatures.

The characteristic feature of the invention is the use of a plurality of thermally responsive elements to actuate a single control device, together with means for placing any one of said elements in operative relation with the control device while holding the other element or elements out of such relation.

The form of the control device is not essential as the inventive idea may be embodied in a wide range of devices, but I illustrate it as applied to a thermostat of the type shown in the patent to Smith and Hofstad No. 1,045,902, granted December 3, 1912, that being one form of device with which I have used it, and with which its various advantages may be attained.

In the drawings :-Figure 1 is a side elevation of the complete control valve, certain portions being shown in section and the easing being omitted. Fig. 2 is a front elevation of the same; Fig. 8 is a section on the line 3 3 of Fig. 2; and Fig. 4 is a perspective view of the thermally responsive elements mounted on their individually adjustable supports.

In the drawings, 1 represents the main frame of the device, 2 is the casing of the supply and exhaust valve for the motor (not shown) to be controlled by the device,

3 is the stem of the said supply and eX-.

ing of valve 7, thus causing the collapse or distention of the diaphragmin chamber and the consequent movement of the control valve in c sing; 2, alternately between its admission and exhaust positions.

All the above is characteristic of the Johnson system of temperature regulation and is set forth in the above mentioned patent.

lNhile I prefer to apply the present invention to the above type of device many other control mechanisms may be substitilted.

The thermally responsive elements consist of two bimetallic bars 9 and 10 whose curvature varies with temperature variations. The free ends of the bars 9 and 1.0 are adapted individually to engage and open valve 7 in opposition to the action of the weighted arms 8 when the temperature passes a certain point characteristic of the adjustment of the bar. The bars are each carried in corresponding brackets 1.1 and 12 supported on resilient tongues 13 and 14 carried by frame 1. An adjusting screw 15 bears on bracket 11 and a screw 16 on bracket 12 and when turned flex the tongues 13 or 14: to effect an adjustment of the corresponding bar. The screws 15 and 16 carry pointers 17 which read on graduations ondial plate 18. A lockout arm 19 is pivoted on plate 18 and has a head 20 which may alternately engage either bar 9 or 1.0 to hold it back out of operative relation with valve 7, or in its midposition may so hold both bars. Thus the two bars 9 and 10 may be individually adjusted to maintain different characteristic temperatures, one bar being for example rendered operative during the day and the other during the night. This feature is of considerable value in hos pitals and the like where it has been found that the wear incident to the daily readjustment of the adjusting screw in thermostats having a single bar ultimately destroys the accuracy of the thermostat.

it will be a pparent that when the bars are adjusted for different temperatures the free end of one bar will always stand forward of the free end of the other, so that the other would never be operative even if unre strained, unless the first bar be held out of engagement. Consequently in cases where one bar will always be set for a higher temperature than the other, the lockout 19 need only be arranged to lock out or'release the bar which first comes into action. I prefer however to arrange it to lock out both as in that event either bar may be set for the higher temperature.

Obviously also more than two bars may be used with a lockout 19adapted to permit only one to operate at a time or adapted to lock them out in order of their temperature adjustments.

As a rule the screws 15 and 16 and the lockout 19 are set by a removable key to prevent unauthorized changes in adjustment.

Having thus described my intention, what I claim is 1. The combination of a control mechanism; a plurality of thermally responsive operation of said control mechanism, the

first of said elements normally responding in advance of the other; and a stop movable to engage said first element and hold the same in inoperative position.

3. The combination of a control mechanism; a pair of thermostatic bars adapted individually to control the operation of said mechanism; individual means for adjusting said bars to adjust the temperature at which they function; and a lookout device adjustable to hold either of said bars in inoperative position.

4:. The combination of a control mechanism; a pair of thermostatic bars adapted individually to control the operation of said mechanism; and a lockout device adjustable to hold either of said bars in inoperative position.

5. The combination of a control mechanism; a pair of thermostatic bars adapted individually to control the operation of said mechanism, the first of said bars becoming operative in advance of the other; and a device adapted alternatively to hold said first bar in inoperative position or release the same.

6. The combination of a control mechanism adapted itself to be controlled by the opening and closin of a leak port formed therein; a valve a apted to open and close said port; a pair of thermostatic bars adapted individually to actuate said valve; individual means adapted to adjust said bars to adjust the temperatures at which they function; and a lockout member movable alternately to hold one or the other of said bars in inoperative position.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CARL F. JOHNSON.

Witnesses:

F. M. ZEALLEY, L. M. WALSH. 

